A majority of them actually talk in general Tamrielic! The one exception however would be Ra'si, who for most of her childhood grew up on the streets in Northern Elsweyr, the province of Anequina!
Some of this would bleed into Daro'Nasi's (Tuna's) speech, but Tuna still mostly speaks in General Tamrielic Ways! (Her Khajiiti speech tends to come out when she is agitated, or is just being a tease~)

He the funny lil fast boi look at him go :)

GOOD stuff, yes, please, MORE of that!~

It'd be an ODD request... But Ra'si desperately needs the coin, if that grumble of her stomach is anything to go off of~ Just don't keep her for too long, she's in a hurry!

Definitely keeping to realistic weight gain and all, Neo doesn't really have an end-goal though! Just, "bigger... and bigger~" Until her belly rolls spill out the sides of the bed, until they start to reach the ends of the room, she'll get bigger and bigger for her loving feeder!

Neo wasn't always the gargantuan tub of lard she is now! She used to be rail-thin and awfully frail; she found it difficult to gain weight on her own despite trying to eat more and more, but she didn't have it in her to stuff herself-
It wasn't until Neopolitan met her soon-to-be wife Sashimi that she could finally realize her fantasy of becoming the ultimate feedee, with Sashimi herself always wanting to care for a growing, hungry fatty and be their forever-feeder~
Aside from being a loyal feedee to her spouse, Neopolitan also enjoys watching lots of anime, and will talk Sashimi's ear off about some popular shonen shows~

Needle had been kept captive on a Dres Plantation in Vvardenfell for quite some time, but had escaped after a bloody confrontation! For a lot of her adventures, Needle travels around Vvardenfell to save fellow Khajiiti and Argonian slaves held captive on the island, eventually coming in to the Twin Lamps and working alongside them for some time; at least... until the Khajiit contracted Vampirism-

Most responsible one would be Ra'si, easy~ But as for the least responsible... Likely the Argonian Noble from Auridon named Bites-too-Much!
Bites would likely be glutting her face and making a mess of some well-stacked dinner table as food crumbs go flying about; all while Ra'si just tries to be on stand-by once the Argonian inevitably ends up riddled with the mother of all belly aches!~

Neopolitan is a rosy-cheeked mountain of blubber for a Gardevoir, with chocolate-colored hair and a milky-white complexion!
You'll rarely ever see her wear anything though, nothing fits her anymore save for maybe some king-sized bedding~

He's doing fine, he's sipping from his juice box and watching the Dirty-Dan episode of Spongebob :)

She'd likely be a Just-chatting streamer who... doesn't do much chatting to be honest-
She's too focused brewing potions on camera, and takes her work VERY seriously in order to make the best brews! She might not even realize all the emotes and chat-spam whenever she accidentally shows off way too much in her already light work clothes~

That chubby Koopa lady was finally let out... eventually~ After the Piranha Plant realized she couldn't quite digest a Koopa Shell THAT massive!
As a side, now that Koopa has a new breath-holding record! ...She doesn't wanna test that again anytime soon-

My Tabaxi/Gnoll Barbarian Viria has to have the strongest and most acid-filled stomach by far! She needs it with how often she gulps down helpless morsels into that gurgling pit of a belly! Though, when it's empty and hungry, it gets awfully angry and noisy...